This invention relates to preparation of symmetrical dichloroacetone. More particularly, the invention is concerned with a superior new method of preparing symmetrical 1,3-dichloroacetone in improved yields utilizing continuously regenerated iodine chloride.
Dichloroacetone is useful as a cross-linking agent for polymers and wood pulp. It is also useful as a chemical intermediate in the preparation of germicides, fungicides and insecticides.
Chloroacetones have been prepared by chlorination of acetone according to various procedures. U.S. Pat. No. 2,635,118 discloses the preparation of di- and trichloroacetones by introducing chlorine and acetone into a mixture of di- and trichloroacetones. U.S. Pat. No. 3,265,740 discloses chlorination of acetone to the hexachloro derivative. U.S. Pat. No. 3,346,646 discloses the reaction of 1-chloro- or 1,1-dichloroacetone with aqueous hypochlorous acid solution to give 1,1,1-trichloroacetone. U.S. Pat. No. 3,397,240 discloses a process for making monohaloacetone and identifies overchlorinated by-products as 1,1-dichloroacetone and 1,3-dichloroacetone obtained in a ratio of about 2-4:1, respectively.
Symmetrical 1,3-dichloroacetone is particularly useful as a chemical intermediate because of the disposition of the chlorine substituent on the 1 and 3 positions. However, 1,3-dichloroacetone is difficult to prepare since direct chlorination of acetone leads to 1,1-dichloroacetone as the major product. More elaborate procedures of preparing 1,3-dichloroacetone include the reaction of 1,3-di-iodoacetone with silver chloride (Annalen 192, 93) by the chromic acid oxidation of symmetrical dichloroisopropyl alcohol (Berichte 4, 562) and by reaction of hydrochloric acid with chloroethoxyacetoacetic ester (Annalen 269, 18). The reaction of acetone and iodine chloride is disclosed in Z. fur chem., 1867, 375 and with iodine trichloride in Annalen, 192, 89.